Carpet underpads must generally exhibit the properties of cushionability, flexibility and durability in order to achieve their full utility. As such, carpet underpads usually comprise a foamed material having an open cell structure. Currently, carpet underpads are fabricated using foamable materials based on urethanes. A drawback to using foams based on urethanes is that when burned they give off noxious and poisonous gases such as isocyanate. In order to render the underpads safer, blowing agents (also referred to as foaming agents) based on butane have been used, but this is expensive and non-economical. Blowing agents based on fluorocarbons are also known but are not acceptable from an environmental point of view.